[Mesa-dev] [PATCH 1/4] gallium/radeon: notify all contexts when cmasks are enabled/disabled

[Bas Nieuwenhuizen]

FWIW The series is
Reviewed-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>

- Bas

On Thu, Mar 10, 2016 at 12:07 AM, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
> From: Nicolai Hähnle <nicolai.haehnle at amd.com>
>
> There is an annoying corner case that I stumbled across while looking into
> piglit's arb_shader_image_load_store/execution/load-from-cleared-image.shader_test
> (which can be easily adapted to demonstrate the bug without the
> ARB_shader_image_load_store extension)
>
> When we bind a texture and then clear it using glClear (by attaching it
> to the current framebuffer) for the first time, we allocate a separate
> cmask for the texture to do fast clear, but the corresponding bit in
> compressed_colortex_mask is not set. Subsequent rendering will use
> incorrect data.
>
> Conversely, when a currently bound texture with an existing cmask is
> exported leading to that cmask being disabled, the compressed_colortex_mask
> bit will remain set, leading to an assertion later on in debug builds.
>
> Since iterating through all contexts and/or remembering where every
> texture is bound would be costly, and cmask enable/disable should be
> rare, we will maintain a global counter to signal contexts that they
> must update their compressed_colortex_masks.
>
> This patch introduces the global counter, and subsequent patches will
> do the mask update.
> ---
>  src/gallium/drivers/radeon/r600_pipe_common.h | 7 +++++++
>  src/gallium/drivers/radeon/r600_texture.c     | 3 +++
>  2 files changed, 10 insertions(+)
>
> diff --git a/src/gallium/drivers/radeon/r600_pipe_common.h b/src/gallium/drivers/radeon/r600_pipe_common.h
> index d20069e..cf8dcf7 100644
> --- a/src/gallium/drivers/radeon/r600_pipe_common.h
> +++ b/src/gallium/drivers/radeon/r600_pipe_common.h
> @@ -335,6 +335,12 @@ struct r600_common_screen {
>          */
>         unsigned                        dirty_fb_counter;
>
> +       /* Atomically increment this counter when an existing texture's
> +        * metadata is enabled or disabled in a way that requires changing
> +        * contexts' compressed texture binding masks.
> +        */
> +       unsigned                        compressed_colortex_counter;
> +
>         void (*query_opaque_metadata)(struct r600_common_screen *rscreen,
>                                       struct r600_texture *rtex,
>                                       struct radeon_bo_metadata *md);
> @@ -406,6 +412,7 @@ struct r600_common_context {
>         unsigned                        initial_gfx_cs_size;
>         unsigned                        gpu_reset_counter;
>         unsigned                        last_dirty_fb_counter;
> +       unsigned                        last_compressed_colortex_counter;
>
>         struct u_upload_mgr             *uploader;
>         struct u_suballocator           *allocator_so_filled_size;
> diff --git a/src/gallium/drivers/radeon/r600_texture.c b/src/gallium/drivers/radeon/r600_texture.c
> index 1a8822c..6b2d909 100644
> --- a/src/gallium/drivers/radeon/r600_texture.c
> +++ b/src/gallium/drivers/radeon/r600_texture.c
> @@ -287,6 +287,7 @@ static void r600_texture_disable_cmask(struct r600_common_screen *rscreen,
>
>         /* Notify all contexts about the change. */
>         r600_dirty_all_framebuffer_states(rscreen);
> +       p_atomic_inc(&rscreen->compressed_colortex_counter);
>  }
>
>  static void r600_texture_disable_dcc(struct r600_common_screen *rscreen,
> @@ -603,6 +604,8 @@ static void r600_texture_alloc_cmask_separate(struct r600_common_screen *rscreen
>                 rtex->cb_color_info |= SI_S_028C70_FAST_CLEAR(1);
>         else
>                 rtex->cb_color_info |= EG_S_028C70_FAST_CLEAR(1);
> +
> +       p_atomic_inc(&rscreen->compressed_colortex_counter);
>  }
>
>  static unsigned r600_texture_get_htile_size(struct r600_common_screen *rscreen,
> --
> 2.5.0
>
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